Remove some obsolete return by refs

[swissspidy]

[21792] / #21839 removed some unnecessary return by reference usage in core. However, it did not properly remove the ampersands from the function signatures.

For example, the signature of wp_get_post_revision is still function wp_get_post_revision( &$post, $output = OBJECT, $filter = 'raw' ), which messes with static analysis.

I suggest auditing the usage, starting with the functions touched by that commit, and removing the ampersands where possible.

Core ticket: https://core.trac.wordpress.org/ticket/64643

Take it or leave it, but Gemini CLI found some additional possibilities:

src/wp-admin/includes/class-wp-upgrader-skin.php

@@ -83 +83 @@
          *
          * @param WP_Upgrader $upgrader
          */
-        public function set_upgrader( &$upgrader ) {
+        public function set_upgrader( $upgrader ) {
                 if ( is_object( $upgrader ) ) {
-                        $this->upgrader =& $upgrader;
+                        $this->upgrader = $upgrader;
                 }
                 $this->add_strings();
         }

src/wp-includes/class-wp-hook.php

@@ -375 +375 @@
          *
          * @since 4.7.0
          *
-         * @param array $args Arguments to pass to the hook callbacks. Passed by reference.
+         * @param array $args Arguments to pass to the hook callbacks.
          */
-        public function do_all_hook( &$args ) {
+        public function do_all_hook( $args ) {
                 $nesting_level                      = $this->nesting_level++;
                 $this->iterations[ $nesting_level ] = $this->priorities;
 

src/wp-includes/deprecated.php

@@ -3111 +3111 @@
  *
  * @param array $pages list of page objects
  */
-function update_page_cache( &$pages ) {
+function update_page_cache( $pages ) {
         _deprecated_function( __FUNCTION__, '3.4.0', 'update_post_cache()' );
 
         update_post_cache( $pages );
@@ -3177 +3177 @@
  * @deprecated 3.5.0 Use get_post_ancestors()
  * @see get_post_ancestors()
  *
- * @param WP_Post $post Post object, passed by reference (unused).
+ * @param WP_Post $post Post object (unused).
  */
-function _get_post_ancestors( &$post ) {
+function _get_post_ancestors( $post ) {
         _deprecated_function( __FUNCTION__, '3.5.0' );
 }
 

src/wp-includes/nav-menu-template.php

@@ -324 +324 @@
  *
  * @param array $menu_items The current menu item objects to which to add the class property information.
  */
-function _wp_menu_item_classes_by_context( &$menu_items ) {
+function _wp_menu_item_classes_by_context( $menu_items ) {
         global $wp_query, $wp_rewrite;
 
         $queried_object    = $wp_query->get_queried_object();

src/wp-includes/pomo/entry.php

@@ -114 +114 @@
                  *
                  * @param Translation_Entry $other Other translation entry.
                  */
-                public function merge_with( &$other ) {
+                public function merge_with( $other ) {
                         $this->flags      = array_unique( array_merge( $this->flags, $other->flags ) );
                         $this->references = array_unique( array_merge( $this->references, $other->references ) );
                         if ( $this->extracted_comments !== $other->extracted_comments ) {

src/wp-includes/pomo/po.php

@@ -486 +486 @@
                  * @param Translation_Entry $entry
                  * @param string            $po_comment_line
                  */
-                public function add_comment_to_entry( &$entry, $po_comment_line ) {
+                public function add_comment_to_entry( $entry, $po_comment_line ) {
                         $first_two = substr( $po_comment_line, 0, 2 );
                         $comment   = trim( substr( $po_comment_line, 2 ) );
                         if ( '#:' === $first_two ) {

src/wp-includes/pomo/translations.php

@@ -130 +130 @@
                  * @param Translation_Entry $entry Translation entry.
                  * @return Translation_Entry|false Translation entry if it exists, false otherwise.
                  */
-                public function translate_entry( &$entry ) {
+                public function translate_entry( $entry ) {
                         $key = $entry->key();
                         return $this->entries[ $key ] ?? false;
                 }
@@ -220 +220 @@
                  *
                  * @since 2.8.0
                  *
-                 * @param Translations $other Another Translation object, whose translations will be merged in this one (passed by reference).
+                 * @param Translations $other Another Translation object, whose translations will be merged in this one.
                  */
-                public function merge_with( &$other ) {
+                public function merge_with( $other ) {
                         foreach ( $other->entries as $entry ) {
                                 $this->entries[ $entry->key() ] = $entry;
                         }
@@ -235 +235 @@
                  *
                  * @param Translations $other
                  */
-                public function merge_originals_with( &$other ) {
+                public function merge_originals_with( $other ) {
                         foreach ( $other->entries as $entry ) {
                                 if ( ! isset( $this->entries[ $entry->key() ] ) ) {
                                         $this->entries[ $entry->key() ] = $entry;

src/wp-includes/post.php

@@ -6309 +6309 @@
  * @see _page_traverse_name()
  *
  * @param int      $page_id  Page ID.
- * @param array    $children Parent-children relations (passed by reference).
+ * @param array    $children Parent-children relations.
  * @param string[] $result   Array of page names keyed by ID (passed by reference).
  */
-function _page_traverse_name( $page_id, &$children, &$result ) {
+function _page_traverse_name( $page_id, $children, &$result ) {
         if ( isset( $children[ $page_id ] ) ) {
                 foreach ( (array) $children[ $page_id ] as $child ) {
                         $result[ $child->ID ] = $child->post_name;
@@ -7678 +7678 @@
  *
  * @since 1.5.1
  *
- * @param WP_Post[] $posts Array of post objects (passed by reference).
+ * @param WP_Post[] $posts Array of post objects.
  */
-function update_post_cache( &$posts ) {
+function update_post_cache( $posts ) {
         if ( ! $posts ) {
                 return;
         }
@@ -7762 +7762 @@
  *
  * @since 1.5.0
  *
- * @param WP_Post[] $posts             Array of post objects (passed by reference).
+ * @param WP_Post[] $posts             Array of post objects.
  * @param string    $post_type         Optional. Post type. Default 'post'.
  * @param bool      $update_term_cache Optional. Whether to update the term cache. Default true.
  * @param bool      $update_meta_cache Optional. Whether to update the meta cache. Default true.
  */
-function update_post_caches( &$posts, $post_type = 'post', $update_term_cache = true, $update_meta_cache = true ) {
+function update_post_caches( $posts, $post_type = 'post', $update_term_cache = true, $update_meta_cache = true ) {
         // No point in doing all this work if we didn't match any posts.
         if ( ! $posts ) {
                 return;

@westonruter Thanks, I have a plan to remove the ref passed parameter in phase-wise, based on the ticket. I have started with the changes done on mentioed changeset. Next, plan to scan the whole core codebase.

Note: E2E tests are failing for all the latest PRs.